smoking while pregnant

Should you quit cold turkey when you find out you're pregnant or wing yourself off? People are saying they smoked their whole pregnancy so it's okay lol. People are ridiculous. I'm not pregnant I want to know for a friend. I said it's not okay and you're putting your child at risk and mind you she's at 50% chance of miscarriage and people are still telling her it's okay bc they did it. They keep calling me stupid 😂😂🤷🏼‍♀️🤷🏼‍♀️